This invention relates to pliers, and more particularly to improved such pliers of both the (Vise Grip) and non-(Vise Grip) varieties which have large, adjustable jaw spans.
Heretofore most pliers of conventional design have utilized a pair of pivotally connected levers for swinging a pair of clamping jaws toward and away from one another. Such prior art includes so-called vise-type pliers, which are generally similar in configuration and operation to conventional pliers, except that they include a latching or over-center device for locking the jaws against movement once they have been clamped in place around a workpiece. Moreover, at least some such prior devices have included some means for adjusting the maximum spacing or span between jaws.
For example U.S. Pat. No. 3,092,378 discloses a clamping device having at least one adjustable jaw. Although U.S. Pat. No. 1,406,032 shows a vise-type device, its jaw span is not adjustable; and although U.S. Pat. No. 63,356 discloses a pliers-type device with a large jaw span, nevertheless neither jaw is adjustable. Other varieties of pliers or clamping devices are disclosed in U.S. Pat. Nos. 851,794; 3,210,070; 2,995,794; 1,151,772 and 1,380,044, but they do not disclose jaw clamping and adjusting means which enable jaw span adjustment without altering the leverage ratio of the devices
Still another disadvantage of most prior pliers has been the fact that their jaw operating levers usually are pivoted together or fulcrumed intermediate their ends, so that the amount of gripping force which can be applied to the workpiece is rather restricted.
It is an object of this invention, therefore to provide improved, compact pliers which have unusually large, adjustable jaw spans.
Still another object of this invention is to provide improved pliers of the type described which have lever ratios at least equal to or greater than conventional pliers, and which have at least one jaw which can be adjusted to vary the jaw span without altering the the lever ratio of the pliers.
A further object of this invention is to provide improved pliers of the type described which are capable of functioning as conventional pliers, or which can be produced in a vise-grip format, so that they can be used both for gripping and clamping purposes.
Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawings.